Pelican plugin that shows articles published on the same month/day in previous years — an "On This Day" section.

The section is rendered client-side: at build time the plugin writes a JSON map of "MM-DD" → articles to the output, and the bundled JS picks the visitor's local date at page load. The section therefore stays correct on a static host without daily rebuilds, and articles from the visitor's current year are excluded.

Add to PLUGINS in pelicanconf.py:

PLUGINS = [
    ...
    "pelican.plugins.on_this_day",
]

That's it for the Attila theme (needs the version providing the partials/footer_extra.html hook) — the plugin overrides that hook with a placeholder and wires everything up:

<aside id="on-this-day" hidden data-source="{{ SITEURL }}/static/pelican_on_this_day/on-this-day.json">
  <div class="inner">
    <p class="on-this-day-label">{% trans %}On This Day{% endtrans %}</p>
    <div class="on-this-day-grid"></div>
  </div>
</aside>
<script src="{{ SITEURL }}/static/pelican_on_this_day/js/on-this-day.js" defer></script>

The plugin only needs the placeholder <aside> and the script tag somewhere in your templates — no Attila-specific markup or CSS variables required:

<aside id="on-this-day" hidden data-source="{{ SITEURL }}/static/pelican_on_this_day/on-this-day.json">
  <p class="on-this-day-label">On This Day</p>
  <div class="on-this-day-grid"></div>
</aside>
<script src="{{ SITEURL }}/static/pelican_on_this_day/js/on-this-day.js" defer></script>

The JS fills .on-this-day-grid with <a class="on-this-day-item"> entries and removes hidden when there are matching articles. The section stays hidden when there is nothing to show (or when the data file can't be fetched). The bundled CSS (added to CSS_OVERRIDE automatically) styles those classes using --color-background-contrast, --color-content-secondary, and --color-primary custom properties — define them yourself, or skip the bundled CSS (drop on-this-day.css from CSS_OVERRIDE after the plugin adds it) and style .on-this-day-item and friends to match your theme.

• ON_THIS_DAY_MAX_ITEMS (optional, default unlimited) — cap the number of articles shown per day, keeping the newest ones.

• output/static/pelican_on_this_day/on-this-day.json — {"MM-DD": [{"year", "date", "title", "url"}, ...], ...}, newest first, URLs prefixed with SITEURL
• output/static/pelican_on_this_day/js/on-this-day.js — client-side renderer
• output/static/pelican_on_this_day/css/on-this-day.css — appended to CSS_OVERRIDE automatically